Fluid distribution systems, for e.g. heating, cooling and water supply are designed to feed a fluid from a source to a consumption point. Each consumption point typically has a calculated and designed flow or differential pressure requirement. However, depending on the type of hydronic system, the flow requirement is often variable over time and can change with factors like seasonality (e.g. summer or winter), that changes the load from the consumption points, temperature changes of the system fluid, changes in consumption of the system fluid (e.g. for drinking water).
Control valves are frequently used in fluid distribution systems and have a variable opening such that the flow rates can be controlled. Hereby, the flow fed to the consumption point may be varied in an effective manner.
A control valve typically controls the flow by a closing arrangement, the closing arrangement comprising a closing member and a closing member receiving portion arranged to receive the closing member. The closing member may e.g. be a valve rod and a valve plug and the closing member receiving portion a valve seat, or the valve may e.g. be a ball valve where the closing member is shaped as a ball which is arranged to rotate and shift its position relative the closing member receiving portion and thereby change the opening degree of the closing arrangement.
The control valve can be arranged in a closed state where no fluid, or only a leakage flow, is allowed to flow through the closing arrangement, and in at least one open state where fluid is allowed to flow through the closing arrangement. In the closed state, the closing member is typically positioned to be in contact, such as in a sealing contact, with the closing member receiving portion.
While the control valves is beneficial for obtaining varying flows in the fluid distribution system, they have the drawback that they require a precise design of the closing member and/or the closing member receiving portion in order for the closed and open states to function properly. For instance, if the closing member is made larger or smaller than intended, it might not be received by the closing member receiving portion in a desired manner. For example, a higher fluid flow than what is allowed might flow through the valve in its closed state and/or the force for moving the closing member might become too large as it is constantly in a high frictional contact with the closing member receiving portion and/or other interior components within the valve.
Thus, it would be desirable to provide a valve having larger manufacturing tolerances.